OTTAWA - Members of Parliament will be asked today to send Canada's courts a message by endorsing a Reform motion re-affirming marriage as the "union of one man and one woman to the exclusion of all others."

Eric Lowther, Reform's family issues critic, says his party wants to pre-empt judges who might one day change the legal definition of marriage to include homosexuals if they are not given clear guidance from elected representatives.

"Our goal is to show some leadership on an issue that I think needs some clarity," said Mr. Lowther. "Marriage is an institution that has been clear in public policy for years. There is a concern today that it is being eroded by some of the initiatives of the Liberal government, deferring to the courts and hiding behind the robes of judges."

The Reform motion was sparked by a Supreme Court decision last month that effectively changed the legal definition of spouse to include same-sex couples. In a ruling on a case known as M v. H, the court struck down as unconstitutional an Ontario family law barring gays and lesbians from seeking alimony when relationships collapse. It ruled that denying homosexual couples the same legal rights and responsibilities as heterosexuals is an affront to "human dignity" and sends a misguided message that gay relationships do not deserve respect.

The decision is expected to affect everything from pensions, property and alimony, to adoption across the country. But the case did not address the issue of marriage, and Anne McLellan, the Justice Minister, yesterday said the government has no intention of changing its legal definition.

Though Ms. McLellan said she had not seen the wording of Reform's motion, she suggested it was redundant. "This government has been quite clear from the outset that we are not interested in redefining the institution of marriage, the definition of marriage, and nor is there any jurisprudence that would require us to do so."

Tom Wappel, Liberal MP for Scarborough-Southwest, said he would be "really, really surprised" if government MPs voted against the marriage motion.

"My reaction will be incredulity and shock," said Mr. Wappel, who plans to vote Yes to the motion.

"This one sounds perfectly reasonable and perfectly acceptable and it is in fact government policy," said Mr. Wappel, part of the Liberals' so-called family values caucus which has resisted government initiatives recognizing same-sex relationships. "If that is what [Liberals] really believe and that is not a snow job, there is no reason to vote against the Reform motion." He added that he believes Reform's political motive is to "out" Liberal MPs who favour altering the definition of marriage.

Gay rights activists suggested the Reform party is overreacting to the recent Supreme Court decision, because homosexual couples are not eager to do battle over redefining marriage.

David Corbett, a lawyer for the Foundation for Equal Families, said gay rights groups fear that cluttering the debate over same-sex benefits with the marriage issue could cause a backlash, and potentially damage gains already made.

"Nobody has proposed a solution that would have marriage as an institution available to same-sex couples," Mr. Corbett said. "It is not constructive contribution to the debate and it is certainly premature."

He said MPs should focus on finding solutions for other same-sex rights instead of worrying about marriage. But Mr. Lowther said Reform is responding to Canadians who fear the M v. Rating onecase "opens the door to homosexual marriage."